Patent GB-1096867-A (GB)
Title: Induced current method simulation device
Inventor: GERSHTEIN GRIGORY MOISEEVICH
IPC: G06G7/40
Filed: 1965-08-24
Abstract: 1,096,867. Simulation device. NAUCHNOISSLEDOVATELSKY INSTITUT MEKHANIKI I FIZIKI PRI SARATOVSKOM UNIVERSITETE. Aug. 24, 1965, No. 36246/65. Heading G4G. In an induced current method simulation device used in apparatus for visual observation and photography of the spectra of space harmonics, for the conversion of space harmonics of the field into time harmonics of induced current, a wedge-shaped probe 1 (Fig. 1)- is suspended from a balance member 2 of dielectric material, and is charged by friction or electrostatic discharge. The balance member 2 is carried by shaft 9 on bearings 10 inside lead screw 11, and is rotatable by motor 13 through dog clutch 12. A model of a linear periodic system to be investigated comprises plural electrodes 18 disposed coplanarly, radially, and symmetrically with respect to the axis of, rotation of the probe; the developed crosssection of model 17 by means of a coaxial cylindrical surface of any radius being geometrically similar to the cross-section of the linear system under investigation, along a longitudinal intersecting plane. It is shown mathematically that the Laplace equations of the fields of model 17 and the linear system being investigated are isomorphous, and that the two dimensional fields are similar. Electrodes 18 are disposed on a dielectric disc 19 fixed on dielectric table 20 by clamp screws, and a unit carried by table 20 enables required variable boundary conditions to be set into the system by modification of currents electrostatically induced in electrodes 18. It comprises (Fig. 8) plural identical adding circuits comprising plural fixed resistors 54 in series with plural variable resistors 55; one pair for each electrode 18 to which they are connected by split spring contacts 32, 33. Contacts 32 are disposed on the bottom of base 19, and contacts 33 connected to the junctions of resistors 54, 55 are fixed to table 20 by screws. The resistors 54 are returned to earth and resistors 55 to a common line to which a variable voltage from potentiometer 30 may be connected, over switch 31 alternately with summation amplifier 56, energizing an oscilloscope and a LF spectrum analyser (Fig. 9, not shown). A current measuring instrument 25 is connected in series with resistor 26 and plug 27 engageable with one of a range of jacks 28 connected to the junctions of each pair of resistors 54, 55, and returned to potentiometer 30, while the meter may be switchably replaced by a plug 62 connectable to an extension meter. In the model (Fig. 1) a flanged sleeve 35 is movable along lead screw 11 by nut 36 with handles 37 to raise and lower the balance 2 and probe 1 against linear scale 43 read against viewer 45 carried by the table 20. In operation, with switch 31 in position A, the values of resistors 55 are set in correspondence with the required potentials to be applied to electrodes 18 of the model of the linear periodic system under investigation, in accordance with required boundary conditions, by inserting plug 27 in successive jacks 24. Initially with a resistor 55 short-circuited, potentiometer 30 is set to produce full-scale deflection of meter 25 and referred to this reading appropriate values of potential are set on the respective jacks by adjusting corresponding resistors 55. Model 17 is then mounted and clamped on table 22 so that contacts 32 engage contacts 33, plug 27 is reversed, switch 31 is placed in position B and motor 13 is energized to rotate shaft 9, balance member 9 and probe 1, which traverses over electrodes 18 and induces time varying signals, proportioned to the spatial distribution of the investigated component of the field in the azimuthal direction of the plane of probe travel, in the adding circuits 24, which are summed with the respective set-in potentials which represent corresponding weighting coefficients, amplified at 56, and applied to an oscillograph and spectrum analyser. The field and its spectrum of space harmonics may be examined at varying distances from the model surface.